Among the well-known techniques for metal removal are the operations of mill cutting and broaching. Each of these operations is generally carried out with different types of cutting tools on different machines.
More specifically, the mill cutting operation is usually performed on a mill with a rotational mill cutter. The mill cutter rotates at a relatively high velocity and has teeth formed on its periphery which cut away at the material of the workpiece as the cutter is fed into engagement with the workpiece.
In the broaching operation the workpiece is shaped by pushing or pulling a broach across a surface of the workpiece. The broach is typically a multiple tooth cutting tool in which the teeth are shaped to give a desired surface or contour, and cutting results from each tooth projecting farther than the preceding one. In a rotary broaching operation the broach is rotated one full revolution in each cycle. In the course of the revolution the broach shapes the workpiece into its finished form. The broaching process is very rapid, accurate, and leaves a finish of good quality. It is employed where duplicate parts must be produced in large quantities and frequently to given dimensions within small tolerances.
An objective of the present invention is to provide a machine which can be adapted to perform either a mill cutting operation or a broaching operation. An important design consideration in this regard is that mill cutting and broaching require different feed characteristics of the work to the cutting tool. The present invention addresses this design consideration and provides a machine which is practical in view of these requirements.